When Donald Trump was a private individual in 2013, he used Twitter to tell President Barack Obama to refrain from attacking Syrian President Bashar al-Assad, who had used chemical weapons to poison his own people.
"No upside and tremendous downside," Trump typed.
As a candidate in 2016, Trump thought likewise. As recently as Tuesday, now President Donald Trump talked the small game. He told the North America's Building Trades' Union's 2017 conference, "I'm not -- and I don't want to be -- the president of the world. I'm the president of the United States. And from now on, it's going to be America First."
That morning, according to White House Press Secretary Sean Spicer, Trump had learned of Assad's use of chemical weapons against his own people. Still Trump resisted Washington's role as global cop.
Yet, on Wednesday Trump stood in the Rose Garden with Jordanian King Abdullah II and declared that he likes to think of himself "as a very flexible person." Assad's attack on children was so horrible that it changed how Trump looked at Damascus.
"I would love to have never been in the Middle East," Trump added. "I would love to have never seen that whole big situation start. But once it started, we got out the wrong way, and ISIS formed in the vacuum, and lots of bad things happened. I will tell you, what happened yesterday is unacceptable to me."
Thursday night, after Trump arrived at Mar-a-Lago for his summit with Chinese President Xi Jinping, Navy destroyers in the eastern Mediterranean launched 59 Tomahawk missiles toward an air base in Syria.
"It's a good start," observed national security analyst Michael Ledeen. In 2002, Ledeen said that he feared President George W. Bush's war in Iraq would cause the U.S. to miss a fleeting window of opportunity to transform Iran from its vibrant grassroots.
These days Ledeen sees three hostile regimes -- Moscow, Tehran and Damascus. Ledeen, by the way, co-wrote the 2016 book "The Field of Fight" with now former Trump National Security Adviser Michael Flynn. Yet Ledeen believes it wasn't foreign policy arguments that nudged Trump -- it was "the pictures."
The result? "This changes the world probably," said Ledeen. "We'll have to wait and see."
Another conclusion -- Obama's way didn't work. In 2013 Russia agreed to locate, secure and destroy Assad's chemical weapons after the Syrian leader gassed his own people. But Secretary of State Rex Tillerson explained, "Either Russia has been complicit or Russia has been simply incompetent in its ability to deliver on its end of that agreement."
With this new chemical weapon attack, Tillerson added, Assad "in effect, is normalizing the use of chemical weapons, which then may be adopted by others." Trump's very human reaction could end up directing foreign policy -- something that rarely happens in this town.
Here's another twist: It could well be that Trump was right to tell Obama not to attack Syria in 2013, yet right to attack Syria himself last week.
In 2013, Obama did not have the stomach for U.S. military involvement in Syria on top of Iraq, Afghanistan and Libya -- and the American public didn't have the stomach either. If the president was not prepared to take the fight with Assad wherever it led, he was shrewd to stop his saber rattling after his feckless warning about his fictional red line.
This month, America's enemies lined up to take their shots at the new commander in chief. North Korea test-fired missiles into the sea and Assad gassed his own people in advance of Trump's meeting with Xi. Trump did not shrink.
In launching missiles toward Syrian air bases, the president seized the moment in a way that established his willingness to use force before bad actors reach a fictitious red line. This gambit works best if not needed again.
But how likely is that? Not very. American Islamic Forum for Democracy founder M. Zuhdi Jasser, a former military doctor and son of Syrians who fled the regime of Assad's father, already called for continuing limited, targeted strikes "focused on reducing Assad's access to resources, especially weapons. Every reduction in his assets is a reduction in his capacity to murder and maim civilians."
A silver lining: Jasser tells Syrians worried that Trump and company were too cozy with Russian President Vladamir Putin, "If they were truly aligned with Russia, this wouldn't have happened."
There goes Trump's strictly "America First" sensibility. Is this the right thing to do? Only time will tell -- and much depends on chance, Moscow and Damascus. If this one attack stops Assad and discourages copycats, the whole world wins.
If not, the world will learn if Trump has the will and the right brainy types gathered around him to make the risk pay off. Trump probably will have to go to Congress seeking authority to use military force in Syria. To sell that package requires a skill set Trump would need to develop. To succeed, Trump will have to be very, very flexible.